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See detailELEMENT DIFFUSION IN THE SOLAR INTERIOR
Thoul, Anne ULg; BAHCALL, J. N.; LOEB, A.

in Astrophysical Journal (1994), 421(2), 828-842

We study the diffusion of helium and other heavy elements in the solar interior by solving exactly the set of flow equations developed by Burgers for a multicomponent fluid, including the residual heat ... [more ▼]

We study the diffusion of helium and other heavy elements in the solar interior by solving exactly the set of flow equations developed by Burgers for a multicomponent fluid, including the residual heat-flow terms. No approximation is made concerning the relative concentrations, and no restriction is placed on the number of elements considered. We give improved diffusion velocities for hydrogen, helium, oxygen, and iron, in the analytic form derived previously by Bahcall & Loeb. These expressions for the diffusion velocities are simple to program in stellar evolution codes and are expected to be accurate to similar to 15%. We find that the inclusion of the residual heat flow terms leads to an increase in the hydrogen diffusion velocity. We compare our numerical results-with those obtained analytically by Bahcall & Loeb using a simplified treatment, as well as with those derived numerically by Michaud & Proffitt. We find that for conditions characteristic of the Sun, the results of Bahcall & Loeb for the hydrogen diffusion velocity are smaller than our more accurate numerical results by similar to 30%, except very near the center where the error becomes larger. The Michaud & Proffitt results differ from the numerical results derived here by less than or similar to 15%. Our complete treatment of element diffusion can be directly incorporated in a standard stellar evolution code by means of an exportable subroutine, but, for convenience, we also give simple analytical fits to our numerical results. [less ▲]

Detailed reference viewed: 11 (2 ULg)
See detailUn élément Epontilles pour LBR5-Report R&D5
Rigo, Philippe ULg

Report (2003)

Detailed reference viewed: 9 (0 ULg)
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See detailElement fluxes, forest floor characteristics and microbial activities under deciduous tree species after conversion of a Norway spruce (Picea abies (L.) Karst.) stand
Bazgir, Masoud ULg; Guillaume, Patricia ULg; Carnol, Monique ULg

Poster (2011, March)

Forest management is currently confronted with major questions, such as how to adapt plantation forests to a changing world. This questioning is not only essential with regard to forest health and ... [more ▼]

Forest management is currently confronted with major questions, such as how to adapt plantation forests to a changing world. This questioning is not only essential with regard to forest health and productivity, but also within the frame of climate mitigation. As Norway spruce monocultures (Picea abies) have been planted in Europe beyond their assumed natural range, are subjected to forest decline and have negative impacts on ecological conditions, conversion into mixed stands has been suggested. Tree species can influence nutrient inputs, soil microbial activity, soil chemistry and nutrient cycling in forest ecosystems. These tree species effects on biogeochemical cycles may vary according to soil type, site characteristics and land use history. The objective of the present study was to quantify element fluxes in throughfall and seepage water, forest floor exchangeable element pools and nitrogen transformations, 12 years after conversion from Picea abies monocultures to a mixed forest stand. Measurements were performed under young and mature Picea abies, Alnus glutinosa (L.) Gaertn., Quercus robur L. and Sorbus aucuparia L. Thus trees have grown on the same site, sharing identical initial soil conditions and site history, so that potential effects on microbial processes and soil properties can be imputed to tree species. Results showed that conversion had a short term impact on nutrient budgets and nutrient cycling in the upper soil layer; in particular on input fluxes of acidifying cations, soil base saturation, net N mineralization and nitrification. [less ▲]

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See detailElement removal in harvested tree biomass: scenarios for critical loads in Wallonia, south Belgium
Bosman, Bernard ULg; Remacle, Jean; Carnol, Monique ULg

in Water, Air & Soil Pollution : Focus (2001), 1

The critical load concept is now widely used as a tool for developing emission control policies in Europe. As a signatory country of the Convention of Long-Range Transboundary Air Pollution, critical ... [more ▼]

The critical load concept is now widely used as a tool for developing emission control policies in Europe. As a signatory country of the Convention of Long-Range Transboundary Air Pollution, critical loads for acidity, nutrient nitrogen, nitrogen and sulphur have been calculated for the Flemish and Walloon regions in Belgium. This paper describes the methodology used for estimating critical loads for forest soils in the Walloon region according to the Steady-State Mass Balance equations. As an example the methodology was applied to the catchment `Waroneu', situated in a sensitive area of the Haute Ardenne. Main input parameters to the equations were derived from precipitation and runoff data of the catchment study. Improved estimates of nitrogen uptake (Nu) and base cation uptake (BCu) were obtained by intensive sampling of Picea abies and Quercus robur trees. Nutrient contents (Ca, Mg, K, N) and nutrient to nitrogen ratios of Picea abies reflected the poor soil quality at a site with high N deposition. Quercus robur nutrient contents increased from stem to higher order branches with a high proportion of nutrients located in the bark. However the simulation of stem only harvesting had a minor effect on critical loads. Measured wood densities were lower than reported literature values with a main effect on Nu and BCu estimates. The use of recommended default values and/or data derived from the experimental site resulted in a wide range of critical loads, some of which were largely overestimated. Results demonstrated the importance of site specific data for critical load calculations. [less ▲]

Detailed reference viewed: 23 (4 ULg)
See detailElement-Free Galerkin Method for Crack Propagation
Ponthot, Jean-Philippe ULg; BELYTSCHKO, T.

Conference (1999)

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See detailElemental 2D imaging of paintings with a mobile EDXRF system
Hocquet, François-Philippe ULg; Calvo Del Castillo, Helena ULg; Cervera Xicotencatl, Ariadna ULg et al

in Analytical and Bioanalytical Chemistry (2011), 399(9), 3109-3116

Imaging techniques are now used commonly and intensively in cultural heritage object analysis. Nowadays, many different techniques in nature as well as many applications exist, where they can be applied ... [more ▼]

Imaging techniques are now used commonly and intensively in cultural heritage object analysis. Nowadays, many different techniques in nature as well as many applications exist, where they can be applied. X-ray radiography and infrared reflectography as well as UV photography are some of the most applied techniques. The study of works of art usually requires these techniques to be non-invasive. Furthermore, they are frequently required to perform in situ analysis. A few years ago, our laboratory developed a mobile energy-dispersive X-ray fluorescence and UV-vis-NIR coupled spectrometer, especially designed for fieldwork studies, where all three techniques can be applied strictly at the same site of analysis. Recent developments on a new positioning system have now allowed us to perform 2D elemental mappings with our equipment, which is especially well adapted to painting analysis. The system control is carried out entirely through a laptop computer running a dedicated homemade software. The positioning is achieved by means of a CCD camera embedded in the system and controlled via a Wi-Fi connection through the computer. The data acquisition system, which is made through a homemade multichannel pulse height analyzer, being also managed via the software mentioned above, goes through an Ethernet connection. We will present here the new developments of the system and an example of in situ 2D elemental mapping applied on an anonymous oil painting on wood panel. The discovery of a hidden painting under this oil painting makes it a good choice for a first example of 2D large scan with a mobile instrument. © Springer-Verlag 2010. [less ▲]

Detailed reference viewed: 110 (30 ULg)
See detailElemental and Isotopic Abundances in Metal-Poor Stars
Magain, Pierre ULg

in Walsh, J. R.; Danziger, I. J. (Eds.) Science with the VLT, Proceedings of the ESO Workshop held at Garching, Germany, 28 June - 1 July 1994 (1995)

Not Available

Detailed reference viewed: 4 (0 ULg)
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See detailThe elementary reactions of energy selected 1,1-Difluoroethene ions.
Güthe, F.; Weitzel, K.-M.; Baumgärtel, H. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1996)

The dissociative photoionization dynamics of 1,1-difluoroethene has been investigated by TPEPICO using synchrotron radiation. The breakdown diagram has been build. The attention has been focussed on C2HF ... [more ▼]

The dissociative photoionization dynamics of 1,1-difluoroethene has been investigated by TPEPICO using synchrotron radiation. The breakdown diagram has been build. The attention has been focussed on C2HF+ (HF-loss) channel. [less ▲]

Detailed reference viewed: 138 (0 ULg)
See detailElementi di docimologia : valutazione continua e esami
de Landsheere, Gilbert ULg

Book published by La Nuova Italia Editrice (1973)

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See detailElementi di docimologia : valutazione continua ed esami
de Landsheere, Gilbert ULg

Book published by La Nuova Italia (1974)

Detailed reference viewed: 37 (0 ULg)
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See detailÉlements affectant la précision du GPS RTK
Wautelet, Gilles ULg

Conference given outside the academic context (2013)

Detailed reference viewed: 48 (4 ULg)
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See detail« Elements d’actualité fiscale : Taxation des revenus mobiliers, nouvelles obligations de mention dans la déclaration et régularisation fiscale »
Bourgeois, Marc ULg; Garroy, Sabine ULg

in Fiscale Praktijkstudies (2013), 39

La contribution se subdivise en trois parties, chacune envisageant une question particulière. 1) Un premier chapitre a fait la synthèse et le point sur les évolutions du régime de taxation des revenus ... [more ▼]

La contribution se subdivise en trois parties, chacune envisageant une question particulière. 1) Un premier chapitre a fait la synthèse et le point sur les évolutions du régime de taxation des revenus mobiliers, depuis l’entrée en fonction du Gouvernement di Rupo. L’objet du propos est informatif et descriptif. 2) Dans un deuxième temps, nous avons analysé plus en détails le souci de transparence des patrimoines qui anime notre législateur, par le biais de l’introduction de nouvelles obligations de mention dans la déclaration annuelle à l’impôt des personnes physiques (assurances-vie individuelles auprès d’entreprises d’assurance établies à l’étranger ; existence d’une « construction juridique »), ou encore des efforts accomplis avec d’autres Etats membres au niveau de l’Union européenne. 3) Enfin, l’examen de la procédure de régularisation fiscale, telle que réformée par la loi du 11 juillet 2013 a fait l’objet du troisième chapitre. [less ▲]

Detailed reference viewed: 24 (4 ULg)
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See detailEléments d'endocrinologie périnatale
Battisti, Oreste ULg

Learning material (2008)

this presentation concerns practical aspects of hypo- and hyperthyroidism, and insulinic diabetes in the perinatal and neonatal periods

Detailed reference viewed: 53 (9 ULg)
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See detailEléments d'examens complémentaires en médecine sportive : illustrations
Frippiat, Thibault ULg

Learning material (2011)

Quelques illustrations des atteintes fréquentes en médecine sportive, concernant l'endoscopie des voies respiratoires supérieurs (au repos et à l'effort), le test de fonction pulmonaire (IOS) et l ... [more ▼]

Quelques illustrations des atteintes fréquentes en médecine sportive, concernant l'endoscopie des voies respiratoires supérieurs (au repos et à l'effort), le test de fonction pulmonaire (IOS) et l'électrocardiogramme. [less ▲]

Detailed reference viewed: 35 (7 ULg)
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See detailEléments d'immunologie et maladies infectieuses du nouveau-né et de l'enfant
Battisti, Oreste ULg

Book published by Les éditions de l'Université de Liège (2012)

Detailed reference viewed: 89 (17 ULg)
See detailEléments d'une nouvelle géographie industrielle de la Communauté Européenne
Merenne-Schoumaker, Bernadette ULg

Book published by Cahier pédagogique du Ministère de l'Education nationale et de la Culture française (1981)

Folder organized around four themes: importance and evolution of industry, spatial distribution, new trends in localization and Europe facing international changes

Detailed reference viewed: 12 (0 ULg)
See detailEléments d'une phylogenèse de la voix
Servais, Véronique ULg

in Badir, Sémir; Parret, Herman (Eds.) Puissances de la voix. Corps sentant, corde sensible (2001)

The paper points to some animal voices and suggest a kind of animality in human voices that isn't just shouts.

Detailed reference viewed: 39 (1 ULg)
See detailEléments de bioinformatique v3.0
Peulen, Olivier ULg

Learning material (2007)

Detailed reference viewed: 20 (9 ULg)